Outcome of Staphylococcus aureus Bacteremia in Patients with Eradicable Foci versus Noneradicable Foci

Clinical Infectious Diseases, Sep 2003

To determine the outcome of Staphylococcus aureus bacteremia (SAB) on mortality, including the impact of methicillin resistance and an initial delay (⩽48 h) of appropriate antibiotics, a retrospective cohort study including 238 patients with SAB was performed. By logistic regression, noneradicable or noneradicated foci, underlying cirrhosis, and cancer were found to be independent predictors of mortality. In patients with eradicable foci, there were no significant differences in the associated mortality rate between methicillin-resistant SAB (11%) and methicillin-susceptible SAB (13%), and between inappropriate (13%) and appropriate (10%) empirical therapy, respectively (P = .79 and P = .78, respectively). By logistic regression, it was found that, in the subgroup of patients with noneradicable foci, underlying cirrhosis (odds ratio [OR], 3.1) and methicillin-resistant SAB (OR, 2.4) were independently associated with mortality.

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Outcome of Staphylococcus aureus Bacteremia in Patients with Eradicable Foci versus Noneradicable Foci

CID Outcome of Staphylococcus aureus Bacteremia in Patients with Eradicable Foci versus Noneradicable Foci Sung-Han Kim 2 3 Wan-Bum Park 2 3 Ki-Deok Lee 2 3 Cheol-In Kang 2 3 Hong-Bin Kim 2 3 Myoung-don Oh 0 2 3 Eui-Chong Kim 0 1 3 Kang-Won Choe 0 2 3 0 Clinical Research Institute, Seoul National University Hospital , Seoul , Republic of Korea 1 Laboratory Medicine, Seoul National University College of Medicine 2 Internal Medicine 3 Departments of To determine the outcome of Staphylococcus aureus bacteremia (SAB) on mortality, including the impact of methicillin resistance and an initial delay ( 48 h) of appropriate antibiotics, a retrospective cohort study including 238 patients with SAB was performed. By logistic regression, noneradicable or noneradicated foci, underlying cirrhosis, and cancer were found to be independent predictors of mortality. In patients with eradicable foci, there were no significant differences in the associated mortality rate between methicillinresistant SAB (11%) and methicillin-susceptible SAB (13%), and between inappropriate (13%) and appropriate (10%) empirical therapy, respectively (P p .79 and P p .78, respectively). By logistic regression, it was found that, in the subgroup of patients with noneradicable foci, underlying cirrhosis (odds ratio [OR], 3.1) and methicillin-resistant SAB (OR, 2.4) were independently associated with mortality. - Staphylococcus aureus is a major cause of hospital- and community-acquired infections, including bacteremia, endocarditis, pneumonia, septic arthritis, and wound infection. Despite several potent antistaphylococcal drugs, S. aureus bacteremia (SAB) is still a serious infection [ 1 ]. In recent years, some investigators have emphasized the importance of focus identification and eradication in the treatment of SAB [ 2, 3 ]. Furthermore, although the rate of the resistance to methicillin among S. aureus is increasing, the clinical impact of methicillin resistance remains controversial [4]. Besides this, because of the recent emergence of S. aureus resistant to vancomycin [ 5 ], the prudent use of vancomycin is essential. However, with some cases, methicillin-resistant S. aureus (MRSA) infections are not initially suspected because clues for S. aureus infection are lacking, and microbiological results, including antibiotic susceptibility data, are usually unavailable for 2 days. However, the relative effects of a delay in appropriate antibiotic treatment on the outcomes of patients with SAB are also unclear [ 4 ]. In this study, we evaluated the risk factors influencing the outcome of SAB. Furthermore, we compared the outcomes of SAB in patients with eradicable focus versus noneradicable focus and determined the impact of methicillin resistance on the outcome for patients with SAB and the effect of the inappropriate empirical antibiotic treatment on the outcome for patients with SAB. PATIENTS, MATERIALS, AND METHODS Study population. Seoul National University Hospital is a university-affiliated tertiary care hospital with 1500 beds. The hospital provides specialized medical and surgical care, including bone marrow transplantation for adult (115 years of age) patients. All patients with blood cultures positive for S. aureus were identified from a retrospective review of the computerized records of the Clinical Microbiology Laboratory for the period of 1 January 1998 through 31 October 2001. Only the first episode of SAB for each patient was included in the analysis. SAB without clinical significance and SAB with a mixture of organisms being cultivated from their blood samples were excluded. Microbiological tests. Identification of S. aureus was performed with Vitek GPI Cards. Antibiotic susceptibilities were determined using the disk diffusion method, following the recommendations of the NCCLS [ 6 ]. Definitions. Bacteremia was defined as the presence of 1 positive blood culture for S. aureus. It was considered clinically significant if S. aureus was isolated from 1 blood culture and if the patients had signs and symptoms consistent with bacteremia [ 7 ]. No cases in which S. aureus was cultivated only in a peripheral intravenous line were included. SAB was considered to have been community acquired if S. aureus was isolated from cultures of blood samples obtained within 48 h after hospital admission, if the patient had not transferred from another hospital, and if the patient had any symptoms or signs suggestive of infection at admission [ 2 ]. Otherwise, SAB was considered to have been hospital acquired. Previous antibiotic use was defined as treatment with antibiotics for 17 days during the month before the onset of SAB [ 7 ]. Previous surgery was defined as an operation within the month before the onset of SAB [ 7 ]. A history of MRSA colonization was defined as isolation of MRSA from any specimens (i.e., sputum, wound, and urine) within the 6 months before the onset of SAB. A hospital stay was defined as the le (...truncated)


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Sung-Han Kim, Wan-Bum Park, Ki-Deok Lee, Cheol-In Kang, Hong-Bin Kim, Myoung-don Oh, Eui-Chong Kim, Kang-Won Choe. Outcome of Staphylococcus aureus Bacteremia in Patients with Eradicable Foci versus Noneradicable Foci, Clinical Infectious Diseases, 2003, pp. 794-799, 37/6, DOI: 10.1086/377540